This invention relates to a preservative and additive for food and feed. More specifically, one aspect of the invention concerns various acidified clays and minerals as food or feed additive to kill, or inhibit the growth of, harmful microorganisms and to inactivate mycotoxins, such as aflatoxins, present as contaminants in human foods and animal feeds. Another aspect of the present invention relates to a clay of hydrated sodium calcium aluminosilicate with relatively uniform particle size distribution.
Microorganism and aflatoxin contamination of human foods and animal feeds constitutes a serious threat to the health of humans and animals. Generally, microorganisms are considered to be any microscopic or ultramicroscopic animal, plant, bacterium, virus, etc., and aflatoxins (Afs) are harmful by-products of mold growth, which both are potentially fatal to humans and animals. Furthermore, such contamination in human food and animal feeds also can lead to severe economic losses.
Aflatoxins are produced by Aspergillus flarus or A. parasiticus. There are at least four naturally occurring aflatoxins, namely AfB1, AfB2, AfG1 and AfG2, as shown in FIG. 1. Many aflatoxins occur as natural contaminants in a variety of foods and feeds, such as corn, wheat, barley, beans, sorghum, moldy peanuts, mixed feed, and some coffee beans. They are also found as residues in liver, kidneys of pigs. Many of these aflatoxins have been known to be strong carcinogens, thus causing cancers, in humans and they are also capable of eliciting other toxic effects, such as teratogenesis.
Many strategies have been developed to inactivate aflatoxins in foods and feeds and the strategies give varying degrees of success. The strategies include processing the food and feed, biocontrol and microbial inactivation, chemical treatment after structural degradation, dietary modification of toxicity and absorption method to reduce bioavailable aflatoxin. One popular method is to add an non-nutritive adsorbents in contaminated feeds to inactivate the aflatoxin. Various adsorbents have been used, such as aluminas, zeolites, silicas, phyllosilicates, bentonite, activated charcoal, and montmorillonite. In particular, NovaSil Plus™ (hydrated sodium calcium aluminosilicate produced by Engelhard Corporation and available from Trouw Nutrition, USA) has been used to “absorb” and inactivate aflatoxin. See, U.S. Pat. No. 5,178,832 to Timothy D. Phillips, et al.; U.S. Pat. No. 5,165,946 to Dennis R. Taylor, et al.; and K. Pimpukdee, Feed & Livestock, pages 40-43, December 2003/January 2004, the content of each of which is hereby incorporated by reference.
As mentioned above, foods and feeds are very often contaminated with both harmful microorganisms and toxic aflatoxins. The methods currently available to solve these problems usually are those that will either kill harmful microorganisms or deactivate toxic aflatoxins, but not both. Thus, it is desirable to have a method that can both kill the harmful microorganisms and simultaneously deactivate toxic aflatoxins.